中文摘要：

通过在Gleeble1500热模拟试验机上进行单轴热压缩试验，研究了共析钢过冷奥氏体在A1～Ar1之间变形时的动态相变特征。结果表明：共析钢过冷奥氏体在变形过程中动态相变与等温相变具有明显差异。动态相变过程中首先沿原始奥氏体晶界形成先共析铁素体，随后生成的珠光体与等温相变得到的珠光体相比，其片层间距和渗碳体厚度较小。提高应变速率将导致动态相变完成时先共析铁素体含量增加，珠光体片层间距减小而渗碳体厚度略有提高。由此提出过冷奥氏体变形使共析点右移的观点，并给予初步解释。

英文摘要：

The dynamic transformation of undereooling austenite under various strain rates was investigated using single pass isothermal hot compression experiments in eutectoid steel, and thermal-talc calculation was used to disscuss the mechanism governing the dynamic transformation process. The results show that proeutectoid ferrite forms firstly at the prior grain boundaries of austenite before pearlite transformation. The interlamellar space and the thickness of cementite lamellae of the pearlite formed by dynamic transformation of undercooled austernite are smaller than that of pearlite fromed by isothermsl transformation. Increasing the strain rate leads to the increase in the volume fraction of proeutectoid ferrite, the slight increase of the thickness of cementite lamellae and the decrease of the interlamellar space of pearlite formed by dynamic transformation of undercooled austenite. Thus, it is concluded that hot deformation of undercooled austenite leads to the fight-shift of eutectoid point, which is different from the Fe-C equilibrium phase diagram.